Ryoma Obara

Author directory

2026

We introduce InterviewArena, an interview-style multi-agent framework for evaluating large language models (LLMs) under incomplete information. By treating missing information as a single factor, we disentangle missing-information identification from dialogue-based reasoning. Experimental results show that while LLMs can capture relative differences between participants, predicting specific missing information remains unstable, highlighting the need to evaluate these capabilities separately.
Identifying constructive comments from user-generated content is important for improving information discovery and discussion quality on platforms such as YouTube. However, existing resources focus predominantly on English news comments, leaving short-form video platforms underexplored despite their distinct characteristics: comments are shorter, more reactive, and not well captured by popularity signals. In this work, we introduce the first Japanese YouTube Shorts dataset for constructive comment extraction, featuring multi-annotator labels that preserve naturally occurring disagreement. We also develop a real-time system that surfaces constructive comments from a noisy comment stream, evaluated in a preliminary user study. To train under noisy annotation conditions, we combine self-training with high-confidence pseudo-labels and active learning. Experiments show that iterative data expansion improves performance, while our compact task-specific model achieves the highest PR-AUC point estimate among the evaluated systems. These findings demonstrate the value of dataset construction and targeted training for constructive comment extraction in realistic settings. Our dataset and code are available at https://github.com/nlp-hayashi/japanese-youtube-constructive-comments

2025

Retrieval Augmented Generation (RAG) complements the knowledge of Large Language Models (LLMs) by leveraging external information to enhance response accuracy for queries. This approach is widely applied in several fields by taking its advantage of injecting the most up-to-date information, and researchers are focusing on understanding and improving this aspect to unlock the full potential of RAG in such high-stakes applications.However, despite the potential of RAG to address these needs, the mechanisms behind the confidence levels of its outputs remain underexplored.Our study focuses on the impact of RAG, specifically examining whether RAG increases the confidence of LLM outputs in the medical domain.We conduct this analysis across various configurations and models.We evaluate confidence by treating the model’s predicted probability as its output and calculating several evaluation metrics which include calibration error method, entropy, best probability, and accuracy.Experimental results across multiple datasets confirmed that certain models possess the capability to judge for themselves whether an inserted document relates to the correct answer. These results suggest that evaluating models based on their output probabilities determine whether they function as generators in the RAG framework.Our approach allows to evaluate whether the models handle retrieved documents.